I don't understand enough about how Indian government works to answer this question: Why can't they lay down sewers and water supplies in urban areas, at least to start with?
I'll give you an example: the Delhi municipal corporation, the local body responsible for all civil work in the country's capital, has more employees than the Indian Air Force.
A municipal body has more employees than the country's entire Air Force.
Of these, nearly half of employees are "ghost" employees. They don't exist except on paper. Their wages go into the pockets of the local politicians and employees.
India's corruption is mind boggling.
461,500 local NYC government employees - https://www.labor.ny.gov/stats/cesemp.asp
456,452 USAF personnel (315,725 AD airmen, 140,727 civilian employees) - http://www.afpc.af.mil/Air-Force-Demographics/
Also, this takes planning at the city level because, once laid, the sewer needs to connected to a larger pipes so that the waste may be transferred somewhere else. Now, people living in the other area need to be convinced that their fellow humans need the sewers and their roads should be dug up.
The roads being dug up is a placeholder for infrastructure work related to installing pipes. As long as people don't see it as a serious problem, they will try to avoid the inconvenience of installing sewers.
This is just the cynic in me, but sometimes I think politicians let it be a problem so that they can use it in the next election season.
Suffice it to say that people living in slums in India can have a lot of political clout. For example, once a large slum pops up in an urban area, literally no one dares to lawfully remove it, for fear of losing the next local election.
Perhaps the Indian society can't find commonalities to organize beyond tribes (aka 'jati' 'caste'). Of course it's not really 'caste' since the grouping is voluntary, but who are you going to shout at about etymology (the epistemology of an Indian means exactly nothing just so you know).
http://www.deccanchronicle.com/nation/in-other-news/070816/b...
[1] Conveniently those belonging to public figures (politicians, actors..) were given a pass.
India - what I saw from going there was enclaves of prosperity surrounded with barbed wires, 4 meter walls and private army guards. And not a nice places to live everywhere else.
If the authorities and well off does not view the citizens as one of them it is hard to get anything done.